One of the ways to use Iris in the landscape is in the rock garden. Indeed there are a large number of species under 12 inches tall that make perfect rock garden plants,
Many rock gardeners feel that species are more suitable for rock garden use than advanced-generation garden hybrids, as they present a more naturalistic appearance. Among the bearded species most often recommended for rock gardens are the diminutive Iris attica, I. suaveolens, and I. pumila. These are all under six inches in height and come in a range of color forms. I. attica requires a rather dry summer, so this should be taken into consideration. Somewhat larger but still quite suitable are I. reichenbachii, I. schachtii, and most forms of I. aphylla.
Beware of pairing irises with spreading perennials that may inhibit air circulation or crowd the plants.
-- Main.RPries - 2010-05-13